Extract numerical data from any printed, photographed, or scanned spectrum — UV-Vis, IR, Raman, fluorescence, chromatography, and more. On your iPhone, iPad, or Mac.
One-time purchase. No subscription. No data collected. No catch.
Coming soon to the App Store.
Spextract is a spectrum digitisation tool built for scientists, students, and researchers who need to extract numerical data from printed, photocopied, or published spectra. Whether you're working from a textbook, a journal article, a lab printout, or an old instrument report, Spextract converts the visual trace into a clean, downloadable dataset — without needing to rescan the original or contact the instrument manufacturer.
It works with virtually any spectrum type: UV-Vis absorbance, infrared transmittance, Raman scattering, fluorescence emission, NMR, chromatograms, and more. If it has two axes and a continuous trace, Spextract can digitise it.
Take a photo directly in the app or import from your library. Spextract handles images taken at an angle — no need for a perfectly flat, overhead shot.
Drag corner handles to remove perspective distortion, then tap known axis values to calibrate both X and Y. Multi-point calibration handles compressed or non-linear scales.
The app traces the spectrum automatically. Review the result, make manual corrections if needed, then export as CSV or TSV for use in Excel, Python, Origin, or any other tool.
The entire workflow from photograph to exported data typically takes under two minutes for a clean printed spectrum.
Tap Import to choose an image from your photo library, or tap Camera to photograph a printed or photocopied spectrum directly. Photographs taken at an angle are fine — perspective correction handles the rest.
Drag the four coloured corner handles to align with the corners of the spectrum plot area. This removes any keystoning or tilt from the photograph, ensuring that axis calibration and trace extraction are geometrically accurate.
Tap two or more known positions along the horizontal axis and enter their values (e.g. wavelength in nm, wavenumber in cm⁻¹, ppm, or time in minutes). More calibration points improve accuracy for compressed or non-linear axes.
Tap the top and bottom of the vertical scale and enter the corresponding values — absorbance units, % transmittance, intensity counts, or whatever units the original spectrum uses.
Tap Extract to run automatic trace detection. Spextract identifies the spectrum line and converts it to a series of (X, Y) data points mapped to your calibrated axes. Review the overlay to confirm accuracy.
Use the manual correction tools to adjust any sections the automatic extraction missed or misread — for instance, very faint traces or regions with heavy grid lines. When satisfied, tap Export CSV or Export TSV to save the data to Files or share it directly.
Spextract is technique-agnostic. As long as a spectrum has two calibratable axes and a visible trace, the app can extract it. Below are common use cases, but the list is far from exhaustive.
Absorbance or transmittance vs. wavelength (nm). Works with single-beam and double-beam instrument printouts.
Transmittance or absorbance vs. wavenumber (cm⁻¹). Handles both mid-IR and near-IR ranges.
Raman shift (cm⁻¹) vs. intensity. Works with dispersive and FT-Raman instrument outputs.
Emission or excitation spectra. Intensity vs. wavelength from any fluorescence spectrometer printout.
Chemical shift (ppm) vs. intensity. Useful for extracting data from published NMR spectra in papers or textbooks.
Time or volume vs. detector response (UV, RI, FID). Digitise HPLC, GC, or SEC chromatograms from printed reports.
If it has a continuous line on two axes, Spextract can extract it — DSC, TGA, XRD, rheology, and more.
Export formats:
Spextract works best with images that have a clearly visible, continuous trace on a contrasting background. Ideal sources include:
The perspective correction tool handles angled shots, so you don't need to position your camera perfectly above the page.
Accuracy depends on the quality of the source image and the number of calibration points you provide. For a clean, high-contrast printed spectrum with four or more calibration points per axis, accuracy is typically within 1–2 data units — sufficient for most literature comparisons and teaching purposes.
For highest accuracy: use a flat, well-lit photograph (or a scanned image), provide calibration points spread across the full axis range, and use the manual correction tools to fix any mis-traced regions.
Yes. Multi-point calibration handles compressed, expanded, or otherwise non-linear axis scales. Tap additional calibration points in the regions where the scale changes most — Spextract interpolates between them to map pixel positions to axis values accurately.
Use the manual correction tools to draw over any sections that were missed or incorrectly traced. Common causes of extraction errors include grid lines that overlap the trace, very faint or broken lines, and regions where two traces cross (e.g. on a difference spectrum). Manual correction lets you fix these precisely.
Yes. After extracting the first trace, you can select a different trace colour or region and run extraction again to obtain a second dataset. Each trace is exported separately.
The exported file contains two columns — one for each axis — which can be opened directly in:
Yes, completely. All image processing, trace extraction, and calibration happens on-device. An internet connection is never required, and no data is ever sent anywhere. See the Privacy Policy for full details.
Spextract accepts any image format supported by iOS and macOS, including JPEG, PNG, HEIC, TIFF, and PDF page exports. You can also import directly from your Files app, Photos library, or a connected scanner.
If you have a question that isn't answered here, have found a bug, or want to suggest a feature, get in touch by email. I aim to respond within two business days.